Rapid detection system for benzilates

ABSTRACT

The invention is directed to a rapid method for the detection of trace quantities of benzilates comprising the steps of swabbing a surface with a swab moistened with a polyhydric aliphatic alcohol; treating the swab with acetic anhydride, oxidizing agent such as potassium dichromate or ferric chloride, and concentrated dehydrating acid such as sulfuric, polyphosphoric, or trifluoracetic acids; and recording the intensity of color change.

United States Patent [19] Sass et al.

RAPID DETECTION SYSTEM FQR BENZILATES [75] Inventors: Samuel Sass, Bel Air; John J.

Martin, Edgewood; William D. Ludemann, Jr, Kingsville, all of Md.

[73] Assignee: The United States of America as represented by the Secretary of the Army, Washington, DC.

[22] Filed: Sept. 8, 1966 21 Appl. No.: 578,940

[52] US. Cl 23/230 R [51] Int. Cl. G01N 31/22 [58] Field of Search 23/230, 230 R [56] References Cited UNlTED STATES PATENTS 3 432269 3/1969 Guilbault et al. 23/230 R 3,628,915 12/1971 Robertson ..23/23OR Primary Examiner-Benjamin R. Padgett Assistant ExaminerE. A. Miller Attorney, Agent, or Firm-Nathan Edelberg; Robert P. Gibson; Robert W. Church [57] ABSTRACT The invention is directed to a rapid method for the detection of trace quantities of benzilates comprising the steps of swabbing a surface with a swab moistened with a polyhydric aliphatic alcohol; treating the swab with acetic anhydride, oxidizing agent such as potassium dichromate or ferric chloride, and concentrated dehydrating acid such as sulfuric, polyphosphoric, or trifluoracetic acids; and recording the intensity of color change.

8 Claims, N0 Drawings This invention is directed to a process for the detection and quanatitative estimation of benzilates, and more particularly relates to the detection of these compounds on contaminated surfaces.

Broadly, these compounds may bedesignated as ben; zilic esters of basic alcohols. Examples ,of these ,ben'zilates are described in the Sternbach U.S. Pat. No. 2,648,667 issued Aug. 1 l, 1953 and in the Pianfetti et al. US. Pat. No. 3,118,896 issued Jan. 21, l964.

It is well known that benzilates are employed as mydriatics, antispasmodics and psychomimetics. For these reasons of use, it is important from the standpoint of safety that rapid, sensitive, and economical detection systems be available to determine the presence of trace quantities of these compounds that might be present on surfaces or when airborne as aerosols.

Our method consists in contacting a surface suspected of containing the compound with a colorless or white swab fabricated from glass wool, and moistened with a low vapor pressure polyhydric aliphatic alcohol such as ethylene glycol, glycerol, or diethylene glycol. A series of reagents are then added in a sequential order to the swab, thus producing an intense blue color indicating the presence of a benzilate. The blue color is sometimes green-blue in the presence of foreign ma terial. The reagents employed in the order of their use are acetic anhydride, ferric chloride, and a concentrated dehydrating acid such as sulfuric acid.

It is an object of this invention to develop a rapid detection system for benzilate contaminated surfaces.

It is an object of this invention to develop a simple and economical detection system.

It is a further object of this invention to develop a sensitive system capable of detecting micro quantities of a benzilate.

Our detection system for benzilates entails the use of a reagent system that allows the detection and analysis of parts per million. Oxidizing agents such as potassium dichromate can be substituted for ferric chloride, but are less effective. Other strong dehydrating acids such as polyphosphoric and trifluoracetic can also be substituted for the concentrated sulfuric acid. It is to be noted that only a glass wool swab can be used with the latter acid. In all instances, an intense blue color is rapidly formed after the sequential addition of the reagents to the exposed moistened swab.

The products of reaction have not been isolated. However. we have strong evidence which indicates a fluorene compound is produced. The mechanism is believed to be as follows:

benzilate Ae O acetylated benzilate condensed blue substituted lluorcne colored product of lluorene COnC. inso,

EXAMPLE l then followed by., adding concentrated sulfuric acid to the same exposed locality. As little as 2 to 3 ,ug of benzilate. can. be detected on a point source of the-swab which is immediately noticeable by the rapidly formed intense blue color.

v Benzjlates can also-be detected in a similar manner on glass fiberelectrophoresis sheets, glass fiber strip, or thin layerchromatography (glass plate) after development, by. spraying, the area or spot with acetic anhydride, then ferricchloride 1% solution in water), and finally with concentrated sulfuric acid. All spots or bands which contain the benzilic moiety are visualized by the intense blue color that rapidly forms at each lo cation.

EXAMPLE 2 A sample of benzilate in methanol, methylene chlo ride, or chloroform in the range of 10 to 50 ,ug/ml is pipetted into colorimeter tubes. The solvent is carefully evaporated (l00C bath for 15 minutes). 0.5 ml of acetic anhydride is added to the tube by permitting it to flow down the side of the tube. Then 1 ml of ferric chloride (1% solution in water) is added. Concentrated sulfuric acid is added cautiously to bring the volume to 10 ml. After approximately 5 minutes, the color is measured on a spectrophotometer at 600 mp. or on a colorimeter, Klett filter (Corning) number 60.

Calibration curves are prepared using known concentrations of benzilate in the range of l0 to 50 pig/ml according to the procedure supra. From these curves an estimation of an unknown concentration of benzilate is calculated. In this last case, the use is for any system where quantitative measurement is required. For example, aerosol or vapor samples collected on filters or in bubblers or medicinal preparations.

The systems described above are useful in various phases of benzilate manufacture and detection. The moistened swab in conjunction with the sequential ad dition of the reagents have been employed in detecting leaks or spills during the filling operation in munition plants and during the transportation of benzilates.

Although the invention has been described in considerable detail, it is to be understood that variations can be made by those skilled in the art without departing from the spirit of the invention and scope of the claims.

We claim:

1. A rapid method for the detection of trace quantities of benzilates on surfaces, which comprises:

A. swabbing a surface with a polyhydric aliphatic alcohol moistened fibrous swab,

B. applying to said exposed moistened swab, in sequential order, the reagents, acetic anhydride, an oxidizing agent selected from the group consisting of potassium dichromate and ferric chloride, and a concentrated dehydrating acid selected from the group consisting of sulfuric acid, polyphosphoric acid, and trifluoracetic acid,

C. recording the intensity of the rapidly formed intense blue color produced from the presence of the benzilate agent, whereby the original quantity present on the surfaces can be calculated.

2. A method in accordance with claim 1 employing a glass wool swab moistened with ethylene glycol.

3. A method in accordance with claim 2 employing concentrated sulfuric acid as the dehydrating acid.

4. A method in accordance with claim 3 employing ferric chloride as the oxidizing agent.

sisting of sulfuric acid, polyphosphoric acid. and trifluoracetic acid, whereby an intense blue color develops ifa ben zilate is present. 6. A method in accordance with cla im 5 employing 5 a glass wool swab moistened with ethylene glycol.

7. A method in accordance with claim 6 employing concentrated sulfuric acid as the dehydrating acid.

8. A method in accordance with claim 7 employing ferric chloride as the oxidizing agent. 

1. A RAPID METOD FOR THE DETECTION OF TRACE QUANTITIES OF BENZILATES ON SURFACES, WHICH COMPRISES A. SWABBING A SURFACE WITH A POLYHYDRIC ALIPHATIC ALCOHOL MOISTENED FIBROUS SWAB, B. APPLYING TO SAID EXPOSED MOISTENED SWAB, IN SEQUENTIAL ORDER, THE REAGENTS, ACETIC ANHYDRIDE, AN OXIDIZING AGENT SELECTED FROM THE GROUP CONSISTING OF POTASSIUM DICHROMATE AND FERRIC CHLORIDE, AND ACONCENTRATED DEHYDRATING ACID SELECTED FROM THE GROUP CONSISTING OF SULFURIC ACID, POLYPHOSPHORIC ACID, AND TRIFLUORACETIC ACID, C. RECORDING THE INTENSTY OF THE RAPIDLY FORMED INTENSE BLUE COLOR PRODUCED FRM THE PRESENCE OF THE BENZILATE AGENT, WHEREBY THE ORIGINAL QUANTITY PRESENT OF THE SURFACES CAN BE CALCULATED.
 2. A method in accordance with claim 1 employing a glass wool swab moistened with ethylene glycol.
 3. A method in accordance with claim 2 employing concentrated sulfuric acid as the dehydrating acid.
 4. A method in accordance with claim 3 employing ferric chloride as the oxidizing agent.
 5. A rapid method for the detection of trace quantities of benzilates on surfaces, which comprises: A. swabbing a surface containing a benzilate with a fibrous swab moistened with a polyhydric aliphatic alcohol, B. applying to said exposed moistened swab, in sequential order, the reagents, acetic anhydride, an oxidizing agent selected from the group consistinG of potassium dichromate and ferric chloride, and a concentrated dehydrating acid selected from the group consisting of sulfuric acid, polyphosphoric acid, and trifluoracetic acid, whereby an intense blue color develops if a benzilate is present.
 6. A method in accordance with claim 5 employing a glass wool swab moistened with ethylene glycol.
 7. A method in accordance with claim 6 employing concentrated sulfuric acid as the dehydrating acid.
 8. A method in accordance with claim 7 employing ferric chloride as the oxidizing agent. 